1. Field of the Invention
This invention relates to an improvement of the AC driven self shift type gas discharge panel, and more specifically to a new self shift gas discharge panel with improved operability and display employing vertical shift and to a system for driving the same.
2. Description of the Prior Art
The AC driven type gas discharge panel is well known as a display device utilizing gas discharge. This panel, however, requires many drivers for operation so long as it employs a matrix addressing configuration, and the drivers and associated electronic circuits become very expensive. Thus, the self shift type gas discharge panel has been proposed in view of solving such disadvantages of the matrix address system and this type of panel is now under further development.
The self shift type gas discharge panel is basically composed of a panel providing shift channels formed by a periodic arrangement of discharge cells of plural groups with each group generally being driven with a different electrical phase. This driving is such that the discharge spots generated by application of write voltage to the write discharge cells provided at one end of each shift channel are sequentially shifted by making use of the coupling effect between adjacent cells.
As self shift type gas discharge panels of this type, for example, the following are well known; those employing the matrix electrode configuration as is disclosed in U.S. Pat. No. 3,944,875 by Owaki et al. which has been assigned to the same assigned as the present invention; those employing the parallel electrode configuration as shown in U.S. Pat. No. 3,775,764 by J. P. Gaur; and those employing the meander electrode arrangement and the meander channel configuration shown in U.S. Patent application Ser. Nos. 813,627 and 810,747 by Yoshikawa et al. which have been proposed recently and assigned to the same assigned as the present invention.
These self shift panels provide the advantage that they can drastically reduce the number of drivers needed for the common electrodes of the X side or the Y side in the address system (only three or four drivers are required).
On the other hand, however, the known self shift type gas discharge panels have the following disadvantage when used for monitor and keyboard display in a computer terminal. Namely, the self shift displays using such known panels have a configuration in which the data written at the extreme right side of a shift line is horizontally shifted from right to left. Thus the interruption of the display while the data written at the extreme right side of the shift line is shifted to the final display position, is a major cause of operator fatigue. In addition, it is desirable that the keyed-in data be displayed sequentially at the final display position from the left side of the screen each time the data is keyed in, but the known self shift display has the disadvantage that the final display position of each data point cannot be confirmed at the keying time. Here, it may be possible that data of as much as a single row including the data which is previously displayed are updated by using an external memory each time data is input, and thereby display can always be performed at the final display position. However, this method is not practical because the writing speed becomes slower than the keying in operation as the number of data to be displayed in a single row increases, and operator fatique becomes more excessive due to flickering. For example, when the three-character data of "A, B, C" is written by the abovementioned refresh writing for each data point in the panel having the known horizontal shift configuration, the writing operation has the sequence of FIG. 1 (a), (b) and (c). However, since the time required for shifting a discharge spot between adjacent display positions in known driving systems is about 0.4 msec, a time of about 288 msec is required when 7.times.9 dots correspond to one character and 80 characters are to be displayed in a single row with an inter-character spacing of 2 dots [(7+2).times.80.times.0.4=288].
Moreover, for the known self shift type display, random addressing is impossible and therefore if an error is found in the displayed data, all the data of a single row must be updated from the beginning. Thereby, operation is very complicated and time is wasted. In addition, it is very difficult in the existing self shift display to realize revision and tabulation with use of a cursor as can be done with the ordinary matrix display.